Mold Gate Venting Layout for Void-Free Semiconductor Encapsulation

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Solution Overview

Problem

During the encapsulation process of semiconductor SIP modules, voids often form over larger electrical components due to the encapsulant (e.g., epoxy molding compound) flowing towards areas of lesser resistance, leading to inadequate coverage and reduced reliability.

Innovation Solution

The mold gate injector is strategically shifted towards the higher flow resistance path over larger electrical components, and an air vent is incorporated to purge excess air, ensuring even encapsulant distribution and preventing voids.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the mold gate injector is positioned to align with electrical component area, then the encapsulant flows easily over smaller components, but the larger electrical components are starved of encapsulant resulting in voids

Engineering Contradiction:

Improveencapsulant coverage uniformityVSAvoidencapsulation reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The mold gate injector is positioned asymmetrically offset from the center of the substrate strip panel toward the side with larger electrical components. This asymmetric positioning compensates for the higher flow resistance path over larger components, ensuring balanced encapsulant distribution across all components regardless of size differences.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The injector position is locally optimized for each specific layout of electrical components. By offsetting the injector toward the side with larger components, the system creates localized flow compensation that addresses the specific geometric arrangement and flow resistance characteristics of that particular component distribution.

Inventive Principle:

Principle #3Local quality

2Speed

If the encapsulant flows towards areas of lesser resistance, then the flow speed increases, but voids form over larger electrical components due to inadequate coverage

Engineering Contradiction:

Improveencapsulant flow speedVSAvoidencapsulant distribution uniformity

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The mold gate injector is positioned asymmetrically offset from the center toward the side with larger electrical components. This creates an intentional asymmetric flow path that balances the encapsulant distribution by compensating for the higher flow resistance over larger components, ensuring uniform coverage while maintaining appropriate flow speeds.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The injector position parameter is changed from a centered location to an offset location. This parameter modification alters the flow dynamics to achieve better distribution uniformity across components of varying sizes, preventing void formation while maintaining efficient encapsulant flow.

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If the end of the substrate strip panel opposite the mold gate injectors does not completely fill with encapsulant, then the filling time is reduced, but voids remain in the encapsulation over electrical components at the far end

Engineering Contradiction:

Improveencapsulation filling timeVSAvoidencapsulant fill completeness

Core Design Contradiction:

Loss of timeVSManufacturing precision

Solution Approach 1:

The mold gate injector is positioned asymmetrically offset toward the side with larger electrical components and components located at the far end of the substrate strip panel. This asymmetric positioning ensures that the encapsulant flow path is optimized to reach all areas including the far end, achieving complete fill without excessive filling time by balancing the flow resistance across different regions.

Inventive Principle:

Principle #4Asymmetry

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach ensures balanced and complete encapsulant coverage over all electrical components, reducing voids and enhancing the reliability and structural integrity of the semiconductor devices.

Implementation Method 1

the encapsulant, for example epoxy molding compound (EMC), flows over the electrical components on the substrate strip panel

Methodology Applied

Scientific EffectFluid flow:

Implementation Method 2

an air vent is incorporated to purge excess air

Methodology Applied

Scientific EffectAir venting:

Data Source

PatentUS12304122B2Semiconductor manufacturing device and method of enhancing mold gate injector and air vent to reduce voids in encapsulant

Publication Date: 2025.05.20 STATS CHIPPAC LTD

AI summary

A semiconductor manufacturing device has a strip panel and a plurality of electrical components disposed over the strip panel. An encapsulant is disposed over the electrical components using a mold gate injector and directed in a path toward higher flow resistance for the encapsulant over the electrical components. The mold gate injector can be shifted toward a side of the strip panel with the path toward higher flow resistance for the encapsulant. The mold gate injector can have a discharge port smaller than the mold gate injector directed at the path toward higher flow resistance for the encapsulant. The discharge port injector can be shifted toward a side of the strip panel with the path toward higher flow resistance for the encapsulant. An air vent and air tank can be coupled to the mold gate injector to aid in release of excess air from the encapsulant.